JP2008248242A - Polypropylene composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene composition superior in any evaluation on a stability against heat oxidation, a hue, a thermal deformation temperature, a flexural modulus, the resistance to NOx, a processing stability and a surface smoothness. <P>SOLUTION: The polypropylene composition comprises a neutralizer chosen from the group which consists of a metal hydroxide and a carboxylic acid metal salt of 0.001 to 0.5 pts.wt., a specified phenolic antioxidant of 0.01 to 0.5 pts.wt., a specified sulfur-containing antioxidant of 0.01 to 0.5 pts.wt., a specified phosphorous antioxidant of 0.01 to 0.5 pts.wt., a metallosilicate of 0.01 to 0.8 pts.wt., polypropylene of 100 pts.wt., a Bisphenol A type glycidyl ether based epoxy compound of 0.001 or less pts.wt. and 0.001 or less pts.wt. of a carboxylic acid amide with carbon numbers of 8-50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polypropylene composition.

Since polypropylene has excellent physical, chemical and electrical properties, it has recently been used in various fields such as housings for electronic parts, electrical parts, automobile parts and the like. The stability of polypropylene against thermal oxidation is evaluated by measuring the embrittlement life, and the hue of polypropylene is evaluated by the yellowness index (YI) after molding.
In order to improve the stability and hue of polypropylene against thermal oxidation, a polypropylene composition comprising an inorganic filler, a phenolic antioxidant, a sulfurous antioxidant, an amide compound and a bisphenol A glycidyl ether epoxy compound is provided. Patent Document 1 proposes.

JP-A-5-271482 ([Claim 1], [Problems to be Solved by the Invention] [0062])

  Recently, in addition to the above-described evaluation, a polypropylene composition that is excellent in all evaluations of heat distortion temperature, bending elastic modulus, NOx resistance, processing stability, and surface smoothness has been demanded.

[式（１）中、Ｒ_１は、それぞれ独立に、炭素数１〜８の直鎖アルキル基または炭素数３〜８の分岐鎖アルキル基を表し、Ｒ_２はメチル基を表す。Ｘは−Ｃ_２Ｈ_４ＣＯＯ−基を表す。Ｙは、炭素数１〜１８の２価のアルコール残基を表す。該アルコール残基に含まれるメチレン基は、シクロアルキレン基またはヘテロ原子に置換されていてもよく、該シクロアルキレン基に含まれるメチレン基はヘテロ原子に置換されていてもよい。]
（Ｒ_３−Ａ−Ｓ−Ｃ₂Ｈ₄ＣＯ₂）_ｍ−Ｚ （２）
［式（２）中、Ｒ_３は炭素数１２〜１８のアルキル基を表す。Ａは単結合又は−Ｃ_２Ｈ_４ＣＯ_２−基を表す。ｍは１〜４の整数を表す。Ｚは、炭素数５〜１８のｍ価のアルコール残基を表す。］

［式（３）中、Ｒ_４、Ｒ_５、Ｒ_６は、それぞれ独立に、水素原子、炭素数１〜９の直鎖アルキル基、又は炭素数３〜９の分岐鎖アルキル基を表す。］

［式（３）中、Ｒ_４、Ｒ_５、Ｒ_６は、前記と同じ意味を表す。］

（式（５）中、ｑは０以上の数を表す。） Under such circumstances, as a result of intensive studies, the present inventors have arrived at the inventions [1] to [4] below.
[1] 0.001 to 0.5 parts by weight of at least one neutralizing agent selected from the group consisting of hydrotalcites, metal hydroxides and carboxylic acid metal salts, phenolic oxidation represented by the formula (1) 0.01 to 0.5 parts by weight of the inhibitor, 0.01 to 0.5 parts by weight of the sulfur-based antioxidant represented by the formula (2), the compound represented by the formula (3) and the formula (4) 0.01-0.5 parts by weight of at least one phosphorus-based antioxidant selected from the group consisting of the compounds shown, 0.01-0.8 parts by weight of metal silicate, and 100 parts by weight of polypropylene The content of the bisphenol A-type glycidyl ether epoxy compound represented by the formula (5) is 0.001 part by weight or less, and the content of the carboxylic acid amide having 8 to 50 carbon atoms is 0.001 part by weight or less. A certain polypropylene composition object.

[Equation (1), R ₁ each independently represent a linear alkyl group or branched alkyl group having 3 to 8 carbon atoms having 1 to 8 carbon atoms, R ₂ represents a methyl group. X represents _-C 2 _H 4 COO- group. Y represents a divalent alcohol residue having 1 to 18 carbon atoms. The methylene group contained in the alcohol residue may be substituted with a cycloalkylene group or a hetero atom, and the methylene group contained in the cycloalkylene group may be substituted with a hetero atom. ]
_{(R 3 -A-S-C} 2 H 4 CO 2) m -Z (2)
[In the formula (2), _{R 3} represents an alkyl group having 12 to 18 carbon atoms. A represents a single bond or a —C ₂ H ₄ CO ₂ — group. m represents an integer of 1 to 4. Z represents an m-valent alcohol residue having 5 to 18 carbon atoms. ]

Wherein _{(3), R 4, R} 5, R 6 represent each independently a hydrogen atom, a linear alkyl group having 1 to 9 carbon atoms, or a branched chain alkyl group having 3-9 carbon atoms. ]

[In the formula (3), R ₄ , R ₅ and R ₆ represent the same meaning as described above. ]

(In formula (5), q represents a number of 0 or more.)

[2] The composition according to [1], wherein the neutralizing agent is a carboxylic acid metal salt having 8 to 22 carbon atoms.
[3] The composition according to [1] or [2], wherein the neutralizing agent is a hydrotalcite.

[式（１）中、Ｒ_１は、それぞれ独立に、炭素数１〜８の直鎖アルキル基または炭素数３〜８の分岐鎖アルキル基を表し、Ｒ_２はメチル基を表す。Ｘは−Ｃ_２Ｈ_４ＣＯＯ−基を表す。Ｙは、炭素数１〜１８の２価のアルコール残基を表す。該アルコール残基に含まれるメチレン基は、シクロアルキレン基またはヘテロ原子に置換されていてもよく、該シクロアルキレン基に含まれるメチレン基はヘテロ原子に置換されていてもよい。]
（Ｒ_３−Ａ−Ｓ−Ｃ₂Ｈ₄ＣＯ₂）_ｍ−Ｚ （２）
［式（２）中、Ｒ_３は炭素数１２〜１８のアルキル基を表す。Ａは単結合又は−Ｃ_２Ｈ_４ＣＯ_２−基を表す。ｍは１〜４の整数を表す。Ｚは、炭素数５〜１８のｍ価のアルコール残基を表す。］

［式（３）中、Ｒ_４、Ｒ_５、Ｒ_６は、それぞれ独立に、水素原子、炭素数１〜９の直鎖アルキル基、又は炭素数３〜９の分岐鎖アルキル基を表す。］

［式（３）中、Ｒ_４、Ｒ_５、Ｒ_６は、前記と同じ意味を表す。］

（式（５）中、ｑは０以上の数を表す。） [4] At least one neutralizing agent selected from the group consisting of hydrotalcites, metal hydroxides and carboxylic acid metal salts 0.001 to 0.5 parts by weight, phenolic antioxidant represented by the formula (1) Agent 0.01-0.5 part by weight, sulfur-based antioxidant represented by formula (2) 0.01-0.5 part by weight, compound represented by formula (3) and compound represented by formula (4) At least one phosphorus-based antioxidant selected from the group consisting of 0.01 to 0.5 parts by weight, metal silicate 0.01 to 0.8 parts by weight, and polypropylene 100 parts by weight, The composition of the bisphenol A type glycidyl ether type epoxy compound represented by) is 0.001 part by weight or less and the content of the carboxylic acid amide having 8 to 50 carbon atoms is 0.001 part by weight or less. Kneading A method for stabilizing a polypropylene composition characterized by the following.

[Equation (1), R ₁ each independently represent a linear alkyl group or branched alkyl group having 3 to 8 carbon atoms having 1 to 8 carbon atoms, R ₂ represents a methyl group. X represents _-C 2 _H 4 COO- group. Y represents a divalent alcohol residue having 1 to 18 carbon atoms. The methylene group contained in the alcohol residue may be substituted with a cycloalkylene group or a hetero atom, and the methylene group contained in the cycloalkylene group may be substituted with a hetero atom. ]
_{(R 3 -A-S-C} 2 H 4 CO 2) m -Z (2)
[In the formula (2), _{R 3} represents an alkyl group having 12 to 18 carbon atoms. A represents a single bond or a —C ₂ H ₄ CO ₂ — group. m represents an integer of 1 to 4. Z represents an m-valent alcohol residue having 5 to 18 carbon atoms. ]

Wherein _{(3), R 4, R} 5, R 6 represent each independently a hydrogen atom, a linear alkyl group having 1 to 9 carbon atoms, or a branched chain alkyl group having 3-9 carbon atoms. ]

[In the formula (3), R ₄ , R ₅ and R ₆ represent the same meaning as described above. ]

(In formula (5), q represents a number of 0 or more.)

  The polypropylene composition of the present invention is excellent in any evaluation of stability against thermal oxidation, hue, thermal deformation temperature, flexural modulus, NOx resistance, processing stability, and surface smoothness.

Hereinafter, the present invention will be described in detail.
In the polypropylene composition of the present invention, the neutralizing agent is 0.001 to 0.5 parts by weight, preferably 0.01 to 0.3 parts by weight, and particularly preferably 0.02 to 0.0. Contains 2 parts by weight.

Here, the neutralizing agent refers to hydrotalcites such as synthetic hydrotalcite and natural hydrotalcite; metal hydroxides such as calcium hydroxide; calcium stearate, calcium palmitate, aluminum stearate, zinc stearate, It is at least one selected from the group consisting of carboxylic acid metal salts such as calcium myristate, calcium laurate, and magnesium stearate.
Among them, preferred are carboxylic acid metal salts having 8 to 22 carbon atoms and hydrotalcites, and particularly preferred are hydrotalcite, calcium stearate, and calcium palmitate.

The polypropylene composition of the present invention comprises 0.01 to 0.5 parts by weight, preferably 0.01 to 0.2 parts by weight, especially 0.01 to 0.2 parts by weight of the phenolic antioxidant represented by the formula (1) with respect to 100 parts by weight of polypropylene. Preferably, it contains 0.02 to 0.1 parts by weight.
In formula (1), R ₁ each independently represents a linear or branched alkyl group having 1 to 8 carbon atoms. Here, examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a t-pentyl group, and a t-octyl group. Among them, R ₁ is preferably a branched alkyl group having 3 to 8 carbon atoms, particularly preferably a t-butyl group, a t-pentyl group, or a t-octyl group.
In formula (1), R ₂ is a methyl group.

X represents _-C 2 _H 4 COO- group. Usually, the ester group side of X is bonded to Y.

Y represents a divalent alcohol residue having 1 to 18 carbon atoms. The methylene group of the alcohol residue may be substituted with a cycloalkylene group or a hetero atom, and the methylene group of the cycloalkylene group may be substituted with a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, and a sulfur atom.
Specific examples of Y include the residue of triethylene glycol residue, 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane. Groups etc. are preferred.

  Specific examples of the phenolic antioxidant (1) include 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethyl. Ethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane (hereinafter sometimes referred to as (1-1)).

The polypropylene composition of the present invention comprises 0.01 to 0.5 parts by weight, preferably 0.01 to 0.3 parts by weight, especially 0.01 to 0.3 parts by weight of the sulfur-based antioxidant represented by the formula (2) with respect to 100 parts by weight of polypropylene. Preferably it contains 0.02-0.2 weight part.
In Formula (2), R ₃ represents an alkyl group having 12 to 18 carbon atoms such as a dodecyl group, a tetradecyl group, or an octadecyl group. A represents a single bond or a —C ₂ H ₄ CO ₂ — group. m represents an integer of 1 to 4.
Z represents an m-valent alcohol residue having 5 to 18 carbon atoms such as a residue of dodecyl alcohol, a residue of tetradecyl alcohol, a residue of octadecyl alcohol or a residue of pentaerythritol. m represents an integer of 1 to 4.

  Specific examples of the sulfur-based antioxidant (2) include, for example, 3,3′-thiodipropionic acid di-n-dodecyl ester, 3,3′-thiodipropionic acid di-n-tetradecyl ester, 3, 3'-thiodipropionic acid di-n-octadecyl ester (hereinafter sometimes referred to as (2-1)), tetrakis (3-n-dodecylthiopropionic acid) pentaerythrityl ester (hereinafter referred to as (2-2) In some cases).

  In the polypropylene composition of the present invention, the total amount of the phosphorus-based antioxidants represented by the formulas (3) and (4) is 0.01 to 0.5 parts by weight, preferably 0.01 to 100 parts by weight of polypropylene. -0.3 parts by weight, particularly preferably 0.02-0.2 parts by weight. As the phosphorus-based antioxidant, only one of the phosphorus-based antioxidant represented by the formula (3) or the phosphorus-based antioxidant represented by the formula (4) may be used.

In formulas (3) and (4), R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, a linear alkyl group having 1 to 9 carbon atoms, or a branched alkyl group having 3 to 9 carbon atoms. To express. Among them, a hydrogen atom, a methyl group, a t-butyl group, a t-pentyl group, a t-octyl group, a nonyl group, and the like can be given. In particular, a hydrogen atom, a methyl group, or a t-butyl group is preferable.

  Examples of the phosphorous antioxidant (3) include tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite (hereinafter sometimes referred to as (3-1)), and the like. Is mentioned.

  Examples of the phosphorus antioxidant (4) include bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite (hereinafter sometimes referred to as (4-1)), bis (2,6 -Di-t-butyl-4-methylphenyl) pentaerythritol diphosphite and the like.

In the polypropylene composition of the present invention, the content of the bisphenol A-type glycidyl ether-based epoxy compound represented by the formula (5) is 0.001 part by weight or less with respect to 100 parts by weight of polypropylene. By making the epoxy compound (5) 0.001 part by weight or less, it is preferable because the hue of the molded product when the present composition is molded tends to be improved.
Here, q in the epoxy compound (5) is 0 or more. The epoxy compound is a product obtained by reacting bisphenol A and epichlorohydrin with a dehydrochlorinating agent such as caustic soda, and q is usually about 10 to 50 of the epoxy compound commercially available. Yes.
It is preferable that the polypropylene composition of the present invention does not substantially contain the epoxy compound.

In the polypropylene composition of the present invention, the content of the carboxylic acid amide having 8 to 50 carbon atoms is usually 0.001 part by weight or less with respect to 100 parts by weight of polypropylene. Preferably, the carboxylic acid amide is substantially added. It is preferable not to contain. It is preferable that the amount of the carboxylic acid amide is 0.001 part by weight or less because the hue of the molded product when the present composition is molded tends to be improved.
Specific examples of the carboxylic acid amide in the present invention include saturated monocarboxylic acid amides such as erucic acid amide and stearic acid amide, unsaturated monocarboxylic acid amides such as oleic acid amide and behenic acid amide, N-stearylbutyric acid amide, N -Stearyl lauric acid amide, N-stearyl stearic acid amide, saturated dicarboxylic acid amides such as N-stearyl behenic acid amide, N-oleyl oleic acid amide, N-oleyl behenic acid amide, N-butyl erucic acid amide, N-octyl Erucic acid amide, N-lauryl erucic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid Unsaturated dicarbohydrates such as amides Acid amide.

  The polypropylene composition of the present invention is 0.01 to 0.8 parts by weight, preferably 0.1 to 0.75 parts by weight, particularly preferably 0.2 to 0 parts by weight, based on 100 parts by weight of polypropylene. Contains 6 parts by weight.

Here, the metal silicate is one kind selected from the group consisting of alkali metals such as sodium and potassium, metals belonging to Group 2 elements such as calcium and magnesium, metals belonging to Group 3 elements such as aluminum, iron and manganese. It is preferable because mica which is a silicate such as magnesium silicate, aluminum silicate, or aluminum, potassium, magnesium, sodium, iron, and the like is preferable. The low temperature impact resistance, the moldability and the paintability tend to be improved.
Examples of the aluminum silicate include natural aluminum silicates such as kaolin, wax, sericite, bentonite and calcined clay, and synthetic aluminum silicates such as zeolite, zeolex and silteg.
Examples of magnesium silicate include talc.

The metal silicate usually has an average particle size of about 0.5 to 30 μm, preferably 1 to 20 μm. An average particle size of 0.5 μm to 30 μm is preferable because the dispersibility in polypropylene is good and the impact resistance of the obtained polypropylene tends to be improved. Here, the average particle diameter of the metal silicate is a value measured by a sedimentation type automatic particle size distribution analyzer.
The water content of the metal silicate is usually about 0.1 to 1% by weight, preferably about 0.1 to 0.3% by weight. A water content of 0.1% by weight or more is preferable because it is easy to obtain and store, and is preferably 1% by weight or less because troubles such as foaming during polypropylene processing tend to be reduced. Here, the moisture content of the metal silicate is a value measured by the Karl Fischer method.

The polypropylene used in the present invention is a polyolefin having a structural unit derived from propylene as a main component, and further includes a structural unit derived from ethylene, 1-butene, 1-hexene, 3-methyl-1-pentene, 4 -Structural units derived from α-olefins other than propylene such as methyl-1-pentene, structural units derived from diene compounds such as butadiene, ethylidene norbornene, dicyclopentadiene, (meth) acrylic acid, methyl (meth) acrylate , Structural units derived from (meth) acrylic acids such as ethyl (meth) acrylate and ethylhexyl (meth) acrylate, structural units derived from vinyl compounds such as styrene, vinyl chloride, vinyl acetate and vinyl versatate, maleic anhydride It may contain acid anhydrides such as acid and succinic anhydride .
Moreover, you may mix | blend polyolefin other than propylene, such as polyethylene, a polystyrene, and a synthetic rubber, with the composition of this invention. In order to excel in mechanical properties such as flexural modulus and thermal deformation temperature, stability against thermal oxidation and hue of the resulting composition, the content of other polyolefins is usually 10 parts per 100 parts by weight of polypropylene. It is not more than parts by weight, preferably not more than 1 part by weight, particularly preferably not more than 0.1 parts by weight.

The composition of the present invention may further contain other additives within a range that does not affect the performance of the polypropylene composition.
Specifically, 2-hydroxy-4-n-octoxybenzophenone, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (3-t-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate Dimethyl oxalate / 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl ) Amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetra Light stabilizers such as methyl-4-piperidyl) imino}],

  Lubricants such as paraffin, low molecular weight polyethylene wax (molecular weight 10000 or less), low molecular weight polypropylene wax (molecular weight 10000 or less), stearic acid, butyl stearate, hydrogenated castor oil, stearyl alcohol,

Cationic antistatic agents such as primary amine salts, tertiary amine salts, quaternary amine salts and pyridine derivatives,
Sulfated oil, soap, sulfated ester oil, sulfated amide oil, sulfated olefin salt of olefin, fatty alcohol sulfate, alkyl sulfate, fatty acid ethyl sulfonate, alkyl naphthalene sulfonate, alkyl benzene sulfonate Anionic antistatic agents such as oxalate sulfonates and phosphate esters,
Partial fatty acid ester of polyhydric alcohol, ethylene oxide adduct of fatty alcohol, ethylene oxide adduct of fatty acid, ethylene oxide adduct of aliphatic amine or aliphatic acid amide, ethylene oxide adduct of alkylphenol, polyhydric alcohol part Non-ionic antistatic agents such as ethylene oxide adducts of fatty acid esters and polyethylene glycol,
Amphoteric antistatic agents such as carboxylic acid derivatives and imidazoline derivatives,

  Anti-fogging agents such as stearic acid monoglyceride, oleic acid monoglyceride, polyglycerin oleate, sorbitan monolaurate, sorbitan monostearate,

Carbon black, titanium oxide, phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, perylene or perine pigment, quinophthalone pigment, diketopyrrolopyrrole pigment, dioxazine pigment, disazo condensation pigment, benzimidazolone pigment Pigments such as pigments,

Flame retardants such as decabromobiphenyl, antimony trioxide, phosphorus flame retardant, aluminum hydroxide,
Examples thereof include nucleating agents such as sodium benzoate, 2,2′-methylenebis (4,6-di-t-butylphenyl) phosphate, and bis (p-methylbenzylidene) sorbitol.

The composition of the present invention includes, for example, a phosphorus-based antioxidant selected from the group consisting of a neutralizer, a phenol-based antioxidant (1), a sulfur-based antioxidant (2), and the above formulas (3) and (4). It is a mixture of an agent, a metal silicate and polypropylene. Specifically, it can be obtained by dry blending with a batch mixer such as a Henschel mixer or a super mixer.
Moreover, as a different preparation method of this composition, it selects from the group which consists of a neutralizer, a phenolic antioxidant (1), a sulfur type antioxidant (2), said Formula (3), and (4), for example. Phosphorous antioxidant and metal silicate are granulated by, for example, dry extrusion granulation method or stirring granulation, and polypropylene is separately melted at 190 ° C to 300 ° C using a single screw or multi screw extruder. Examples of the method include a method in which the obtained granulated material is fed from a side feeder and granulated into a pellet when extruded.
The polypropylene composition of the present invention may be further subjected to injection molding or extrusion from a T die while being heated at 190 ° C to 330 ° C, preferably 200 ° C to 300 ° C, particularly preferably 210 ° C to 280 ° C. .

Hereinafter, the present invention will be described in more detail with reference to examples and the like. Parts and% represent weight basis unless otherwise specified.
For the examples and comparative examples, those in Table 1 were used.

Example 1
All listed in Table 1, 100 parts by weight of polypropylene, 0.05 part by weight of neutralizer (N-1), 0.05 part by weight of phenol-based antioxidant (1-1), sulfur-based antioxidant 0.05 part by weight of the agent (2-2), 0.05 part by weight of the phosphorus-based antioxidant (4-1) and 0.05 part by weight of the metal silicate are put into a Hensial mixer and mixed at 1000 rpm for 30 seconds. Then, it was melt-extruded with a 30 mmφ twin screw extruder to obtain a polypropylene composition granulated into pellets.
Subsequently, the obtained composition was injection-molded, and the obtained injection-molded test piece (40 mm × 40 mm × 1 mm) was evaluated as follows. In addition, the surface of the obtained injection molding test piece was smooth.
The results are summarized in Table 3. As is clear from Table 3, the polypropylene composition of Example 1 was evaluated for any evaluation of stability against thermal oxidation, hue, thermal deformation temperature, flexural modulus, NOx resistance, processing stability, and surface smoothness. Was also excellent.

(Heat deformation temperature)
The thermal deformation temperature of the injection molded specimen was measured according to JIS K 7202 (1983) B method. The higher the heat distortion temperature, the better the polypropylene resin composition.

(Flexural modulus)
The bending elastic modulus of the injection molded specimen was measured according to JIS K 7171 (1994). The higher the flexural modulus, the better the polypropylene resin composition.

(Stability against thermal oxidation: measurement of embrittlement life in a gear oven)
The injection molded test piece was placed in a gear oven at 150 ° C., and the surface embrittled area was measured. The number of days until the brittle area reached 30% was defined as the brittle life. The more days, the better the stability against thermal oxidation.

(Hue)
The yellowness index (YI) of the injection molded test piece was measured using a color difference meter. It means that the smaller the YI number, the more white and the better the hue.

(NOx exposure test)
(Preparation) Nitrogen oxide gas dyeing fastness tester manufactured by Suga Test Instruments Co., Ltd. An injection molded specimen was suspended in the model GF-5 nitric oxide gas tester.
(Preparation of NOx gas) According to JIS L 0855 (1998), NOx gas was generated and gas bullet NOx gas was collected.
(Exposure test) 10 mL of NOx gas collected in the gas burette was sampled with a gas syringe and injected into the model GF-5. After rotating the propeller and exposing at room temperature for 7 days, the lid was opened and the test piece was taken out, and then YI was measured with a color difference meter. It means that the smaller the YI number, the more white and the better the hue.

(Processing stability)
Pellets (this composition) obtained by melt-kneading with a twin screw extruder were extruded with a 30 mmφ single screw extruder, and the extruded pellets were again extruded with the single screw extruder. The MFR of the pellets after being repeatedly extruded 5 times with a single screw extruder was measured.
MFR was automatically measured according to JIS K 7210 (1976) test conditions, condition 14 in Table 1. A smaller MFR means that the polypropylene composition has better processing stability.

(Examples 1-5, Comparative Examples 1 and 2)
As shown in Table 2, a composition and an injection-molded test piece were obtained in the same manner as in Example 1 by changing the content of metal silicate to 0 to 1 part with respect to 100 parts of polypropylene. In addition, the surface of the obtained injection molding test piece (Examples 1-5, Comparative Examples 1 and 2) was smooth.
The same evaluation as in Example 1 was performed, and the results are shown in Table 3 together with Example 1. Comparative Example 1 is inferior in flexural modulus, heat distortion temperature, stability against thermal oxidation and processing stability, while Comparative Example 2 is inferior in stability against thermal oxidation, whereas the polypropylene compositions of Examples 1-5 are It was excellent in all evaluations of stability against thermal oxidation, hue, thermal deformation temperature, flexural modulus, NOx resistance, processing stability and surface smoothness.

(Examples 6-9, Comparative Examples 3-5)
As shown in Table 4, a composition and an injection-molded test piece were obtained in the same manner as in Example 1 by changing the content of the neutralizing agent to 0 to 1 part with respect to 100 parts of polypropylene.
In addition to the above evaluation items, the roughness of the surface of the injection molded test piece was evaluated based on the gloss value. The results are shown in Table 5. The gloss value was measured at an incident angle of 60 ° and a light receiving angle of 60 ° using a digital gonio-gloss meter manufactured by Suga Test Instruments Co., Ltd., and the surface smoothness was evaluated. A larger number means less surface roughness (smoothness), gloss, and superior surface smoothness.
Comparative Example 3 is inferior in surface smoothness, Comparative Example 4 is inferior in flexural modulus, thermal deformation temperature and thermal oxidation stability, and Comparative Example 5 is in flexural modulus, thermal deformation temperature, thermal oxidation stability and While the surface smoothness is inferior, the polypropylene compositions of Examples 6 to 9 are any of stability against thermal oxidation, hue, heat distortion temperature, flexural modulus, NOx resistance, processing stability and surface smoothness. The evaluation was also excellent.

(Examples 10 and 11, Comparative Examples 3 to 5)
As shown in Table 6, a composition and an injection-molded test piece were obtained in the same manner as in Example 1 by changing the kind of the antioxidant with respect to 100 parts of polypropylene. The surfaces of the obtained injection molded test pieces (Examples 10 and 11 and Comparative Examples 6 to 8) were all smooth.
The same evaluation as in Example 1 was performed, and the results are shown in Table 7. Comparative Examples 6 to 8 are inferior in thermal oxidation stability, processing stability and NOx resistance, but the polypropylene compositions of Examples 10 and 11 have thermal oxidation stability, hue, thermal deformation temperature, flexural modulus. Moreover, it was excellent in any evaluation of NOx resistance, processing stability and surface smoothness.

  The polypropylene composition of the present invention is excellent in any evaluation of stability against thermal oxidation, hue, thermal deformation temperature, flexural modulus, NOx resistance, processing stability, and surface smoothness.

Claims (4)

0.001-0.5 part by weight of at least one neutralizing agent selected from the group consisting of hydrotalcites, metal hydroxides and metal carboxylates, and a phenolic antioxidant represented by the formula (1) 0.01 to 0.5 parts by weight, 0.01 to 0.5 parts by weight of a sulfur-based antioxidant represented by formula (2), a compound represented by formula (3) and a compound represented by formula (4) 0.01-0.5 part by weight of at least one phosphorus-based antioxidant selected from the group consisting of: 0.01-0.8 part by weight of a metal silicate, and 100 parts by weight of polypropylene, The polypropylene composition in which the content of the bisphenol A-type glycidyl ether epoxy compound represented by (5) is 0.001 part by weight or less and the content of the carboxylic acid amide having 8 to 50 carbon atoms is 0.001 part by weight or less. object.

[Equation (1), R ₁ each independently represent a linear alkyl group or branched alkyl group having 3 to 8 carbon atoms of 1 to 8 carbon atoms, R ₂ represents a methyl group. X represents _-C 2 _H 4 COO- group. Y represents a divalent alcohol residue having 1 to 18 carbon atoms. The methylene group contained in the alcohol residue may be substituted with a cycloalkylene group or a hetero atom, and the methylene group contained in the cycloalkylene group may be substituted with a hetero atom. ]
_{(R 3 -A-S-C} 2 H 4 CO 2) m -Z (2)
[In the formula (2), _{R 3} represents an alkyl group having 12 to 18 carbon atoms. A represents a single bond or a —C ₂ H ₄ CO ₂ — group. m represents an integer of 1 to 4. Z represents an m-valent alcohol residue having 5 to 18 carbon atoms. ]

Wherein _{(3), R 4, R} 5, R 6 represent each independently a hydrogen atom, a linear alkyl group having 1 to 9 carbon atoms, or a branched chain alkyl group having 3-9 carbon atoms. ]

[In the formula (3), R ₄ , R ₅ and R ₆ represent the same meaning as described above. ]

(In formula (5), q represents a number of 0 or more.)   The composition according to claim 1, wherein the neutralizing agent is a carboxylic acid metal salt having 8 to 22 carbon atoms.   The composition according to claim 1 or 2, wherein the neutralizing agent is a hydrotalcite. 0.001 to 0.5 parts by weight of at least one neutralizing agent selected from the group consisting of hydrotalcites, metal hydroxides and carboxylic acid metal salts, phenolic antioxidants represented by formula (1) 0. 01-0.5 part by weight, sulfur-based antioxidant represented by formula (2) 0.01-0.5 part by weight, group consisting of compound represented by formula (3) and compound represented by formula (4) At least one phosphorous antioxidant selected from 0.01 to 0.5 parts by weight, 0.01 to 0.8 parts by weight of a metal silicate, and 100 parts by weight of polypropylene, represented by formula (5) Melting and kneading a composition in which the content of the bisphenol A-type glycidyl ether epoxy compound is 0.001 part by weight or less and the content of the carboxylic acid amide having 8 to 50 carbon atoms is 0.001 part by weight or less. Features Method of stabilizing polypropylenes.

[Equation (1), R ₁ each independently represent a linear alkyl group or branched alkyl group having 3 to 8 carbon atoms of 1 to 8 carbon atoms, R ₂ represents a methyl group. X represents _-C 2 _H 4 COO- group. Y represents a divalent alcohol residue having 1 to 18 carbon atoms. The methylene group contained in the alcohol residue may be substituted with a cycloalkylene group or a hetero atom, and the methylene group contained in the cycloalkylene group may be substituted with a hetero atom. ]
_{(R 3 -A-S-C} 2 H 4 CO 2) m -Z (2)
[In the formula (2), _{R 3} represents an alkyl group having 12 to 18 carbon atoms. A represents a single bond or a —C ₂ H ₄ CO ₂ — group. m represents an integer of 1 to 4. Z represents an m-valent alcohol residue having 5 to 18 carbon atoms. ]

Wherein _{(3), R 4, R} 5, R 6 represent each independently a hydrogen atom, a linear alkyl group having 1 to 9 carbon atoms, or a branched chain alkyl group having 3-9 carbon atoms. ]

[In the formula (3), R ₄ , R ₅ and R ₆ represent the same meaning as described above. ]

(In formula (5), q represents a number of 0 or more.)